1. Field of the Invention
The present invention relates to a shock absorber, and more particularly to a hydraulic shock absorber having a damping device to provide an excellent shock-absorbing effect by means of changing the flow rate of oil.
2. Description of Related Art
To improve comfort of driving or riding a vehicle such as a car, motorcycle or a bicycle and to keep shock from being transmitting to the vehicle to cause damage to the vehicle, shock absorbers are always mounted between a frame and wheels of the vehicle. A conventional shock absorber in accordance with the prior art substantially comprises an outer tube, an inner tube slidably combined with the outer tube and a shock-absorbing element. The shock-absorbing element is mounted between the inner tube and the outer tube and may be a spring or oil. A shock absorbing effect is achieved due to the compression of the spring or the flow of the oil inside the tubes.
However, when the shock applied to the wheel is huge, the travel of the inner tube relative to the outer tube is so long to cause the inner tube bump directly against the outer tube. This will cause the shock absorbing effect of the absorber to be eliminated and damage to the absorber and the vehicle. In addition, a resilient bumper is mounted between the inner tube and outer tube to keep the tubes from contacting with each other directly. However, the bumper is easily damaged after a period of use due to exhaustion of resilience.
To overcome the shortcomings, the present invention tends to provide a shock absorber to mitigate or obviate the aforementioned problems.